Conventional digital reprographic systems receive electronic image(s), which are passed to an image processing unit. The image processing unit may be a combination of software and hardware elements that accepts the electronic images from a multiplicity of sources and performs operations needed to convert the images to the format compatible with the output path of the digital reprographic system.
For example, a conventional image processing unit may convert continuous tone image data into binary image data. Moreover, the conventional image processing unit may convert the binary image data into a reduced coverage (economy mode or draft mode) bitmap of binary image data.
Conventional digital reprographic systems convert image data into a reduced coverage (economy mode or draft mode) bitmap of binary image data to save toner or ink usage. The economy mode may have the same resolution as a regular print mode in a conventional digital reprographic system, but toner or ink usage is reduced, by a color table or a transfer function, for example. However, when solid colors (100% coverage) are reduced to a lower coverage, text and fine lines suffer due to halftoning, resulting in jagged text and dithered lines.
Conventionally, when printing in an economy mode, a data stream representing the image may be processed so that the printer uses less marking material (ink or toner) to print the image than it would if the processing was not performed.
More specifically, conventional digital reprographic systems operate by printing a series of dots or spots (pixels) of marking material on a recording medium to produce the rendered image. To reduce the amount of marking material used in rendering, conventionally black (non-white) regions in the image are modified to halftone grey regions. This is conventionally achieved by removing dots or spots (pixels) corresponding to marking material.
However, removing dots or spots (pixels) corresponding to marking material at the edges of text or shape can result in undesirable jaggies (jagged text) or dithered lines.
Thus, it would be desirable to provide a method or digital reprographic system that reduces marking material (toner or ink) usage while preserving the quality of text and fine lines.
Furthermore, it would be desirable to provide a method or digital reprographic system that reduces marking material (toner or ink) usage while rendering text edges and fine lines at 100% coverage and halftoning the inside areas, away from edges, to a lower coverage.
It would also be desirable to process halftoned bitmaps while preserving text edges and fine lines while reducing other areas to much lower coverage, thereby realizing an economy mode rendered image with high quality.